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    <script>
        let arr = [1,'sd',3,5];
        let arr1 = [1,2];
        console.log(...arr);
        // arr.push(arr1);
        arr.push(...arr1);
        console.log(arr);
        let arr2 = [[1],[2],[3]]
        console.log(...arr2);       //[1],[2],[3]
        
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        foo(1,2,3,4);

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